A. Field of the Invention
This invention relates to the electrolytic dissolution of a metal such as copper into an aqueous solution of polyamide-forming salt. Upon melt polymerization of the salt solution, the metal is incorporated into the resulting polyamide.
B. Description of the Prior Art
Nylon 66 and other synthetic linear polyamides are prepared by the melt polymerization of an aqueous solution of the appropriate polyamide-forming salt. Such polyamides are conventionally stabilized against heat degradation by dissolving a copper compound, such as copper acetate, in the aqueous salt solution prior to melt polymerization. Normally, an inorganic halide such as KBr or KI is also added to the aqueous salt solution to enhance the stabilizing effect of the copper compound (U.S. Pat. Nos. 2,705,227 and 3,947,424). Unfortunately, ions such as acetate, potassium, bromide and iodide ions act as impurities, that is, such ions tend to adversely effect melt polymerization, fiber formation and/or properties of the final polymer, for example, acetate anions function as chain terminators and limit the molecular weight of the final polymer and cations such as potassium may interfere with fiber processing (e.g. dyeing) or cause agglomeration of other additives which may be present for other purposes.